104 Baron N. Schilling on the Constant Currents 



of the tropical atmosphere, and so also exert a certain influence 

 on the trade-winds, but cannot possibly develop sufficient force 

 to give rise to those winds. 



We conclude the consideration of the influence of the earth's 

 rotation on air- and sea-currents with the conviction that the 

 existing explanations are altogether insufficient for the currents 

 which flow parallel to the equator, because the rotation of the 

 earth can only inconsiderably alter the direction of an already 

 existing current, whether in air or sea, but can never indepen- 

 dently produce a current of any importance. 



C. Attraction of the Sun and Moon. 

 As is known, all the heavenly bodies attract each other, the 

 force therein developed being, according to the law of the im- 

 mortal Newton, directly as the mass and inversely as the square 

 of the distance between the two bodies. If, therefore, we take 

 as the unit of mass that of the earth, and as unit of distance the 

 semidiameter of the earth, then, according to Newton's law, the 

 force with which the sun attracts the earth's centre will be ex- 



319500 



(23400)' 



with the force 2 *. The ratio of the attractive force of 



the "other heavenly bodies will be readily found in the same 



manner. For example, the force with which Jupiter attracts the 

 earth when nearest to it is one 25th part of that of the moon. 

 The action of all the rest of the heavenly bodies, so vastly dis- 

 tant, is again considerably less. 



Now, as the force with which a given heavenly body (the sun 

 for instance) attracts the earth depends entirely upon the dis- 

 tance between the two, it is self-evident that the parts of the 

 earth's surface which are nearer to the sun must be exposed to a 

 greater attraction than those more distant. This can have no 

 effect on the solid surface of the earth ; but the easily displace- 

 able particles of the sea and the atmosphere must have their 

 equilibrium destroyed by its influence ; and to restore the equi- 

 librium currents must arise. In order to form true ideas of 

 these currents, it is absolutely necessary to investigate more mi- 

 nutely the forces which call them forth, and the action of these 

 forces. Before all things we must realize that we wish to con- 



pressed by /()Q/)nn8 . The moon attracts the centre of the earth 



'D' 



* We have assumed, after Klein (Das Sonnensystem), that the mass of 

 the sun is 319500 times, and that of the moon one 80th part of that of the 

 earth. For the mean distance, we have assumed that the distance of the 

 sun is 390 times that of the moon, whose mean distance we estimate at 60 

 semidiameters of the earth. 



